Verification forms on IOS does not work?

<form class="form" action="http://meca.kz/sendernext.php" method="post">
 <div class="form-group">
 <label>Write the request for calculation</label>
 <input type="text" name="name" id="name" size="30" required placeholder="Your Name and Phone number" aria-describedby="name-format" aria-required="true" pattern=".{6,}"> 
 </div> 
 <button type="submit" class="btn btn-default">Submit</button>
 </form>

Guys a question! Why not fire the validation on IOS devices? Not only in the native Safari but in Google chrome and in other browsers it is on IOS Devices